I haven't spotted Anakin/Vader in the leaks, I think he would have been brought up if he was making an appearance. Would be a pretty big deal. Unless they did some last minute reshoots or something. Like I said, i'd like to see him appear in some form if done correctly. They had conceptual ideas of him returning in Force Awakens, one as some sort of split dark/light side personality that Kylo Ren would apparently interact with. The idea actually sounded pretty interesting.
And yeah I meant Snoke. Haven't seen any sign of him in the leaks. I don't even know if the complete lack of information can be considered much of a spoiler in this case. We may never know who he was, where he came from, why he's so powerful, how he even came to power, why he knows so much about the Sith/Jedi/force/etc, how he infiltrated Ben's mind, what the deal is with his black ring, why he was able to be taken out like such a wuss, etc etc. They built this guy up as the new Palpatine but then deflated it all like a whoopie cushion, not even an attempt at a satisfying or acceptable conclusion to the mysteries behind him.
Now he's being replaced with a rehashed villain from the previous 6 films. An admittedly much more entertaining character/actor I will concede, I hope JJ at LEAST gives Ian some opportunity to ham it the hell up to make things at bit more fun (won't get my hopes up there). I'll freely admit that Snoke felt very bland and cookie cutter to me in the first place. But then Rian had to go leave a big ugly gaping hole behind him. Even the "Snoke is Darth Plagueis" theory (while perhaps predictable) would have been a huge step up from this mess.